Deformable mirrors require securing the mirror to a housing, usually at its outer periphery, and using actuators at multiple locations on the mirror structure. Various linear actuators have been used for this purpose including magnetostrictive and piezoelectric types. In any event they require attachment of the actuator drive mechanism to the mirror structure in a manner which can both push and pull.
This has been accomplished sometimes in the past with a permanent attachment technique such as adhesive bonding, frit bonding or brazing. Replacement of a failed actuator in such a design is either difficult or impossible without damage to the mirror.
Other attachment techniques have been used to facilitate removal. These included designs with retract springs adjacent to the actuators to ensure proper faceplate retraction during push/pull operation. Ultrafine threads were also necessary to facilitate actuator replacement without disturbing the high quality optical surface. Mechanical hysteresis alignment and the galling of threads remained significant performance problems. The complexity associated with a mechanical preloaded attachment mechanism required an intensive and time consuming actuator installation process. This greatly limited its scalability to a structure requiring many hundred actuators on a deformable mirror.
Other designs imposed high stress concentrations in the springplate/faceplate inner face. Even with the difficulties of the prior art attachment mechanisms, they were acceptable since the risk of even one actuator failing in a permanent attachment design prevents even more difficulties.
Thus, there is a need for an attachment mechanism that allows for ease of replacement, does not degrade deformable mirror performance nor the optical surface, that is cost effective and allows for automated actuator installation.